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Thousands of genomes reveal the wild wolf genes in most dogs’ DNA

wild wolf genes in most dogs’ DNA: New research analyzing 2,693 dog genomes reveals most modern dogs carry wolf DNA from ancient hybridization. Discover how wolf genes helped dogs survive and what this means for breeds from Chihuahuas to sled dogs.

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wild wolf genes in most dogs’ DNA
Modern wolves and dogs both descend from an ancient wolf population that lived alongside woolly mammoths and cave bears.
Iza Lyson/500px Prime via Getty Images

Thousands of genomes reveal the wild wolf genes in most dogs’ DNA

Audrey T. Lin, Smithsonian Institution and Logan Kistler, Smithsonian Institution

Dogs were the first of any species that people domesticated, and they have been a constant part of human life for millennia. Domesticated species are the plants and animals that have evolved to live alongside humans, providing nearly all of our food and numerous other benefits. Dogs provide protection, hunting assistance, companionship, transportation and even wool for weaving blankets.

Dogs evolved from gray wolves, but scientists debate exactly where, when and how many times dogs were domesticated. Ancient DNA evidence suggests that domestication happened twice, in eastern and western Eurasia, before the groups eventually mixed. That blended population was the ancestor of all dogs living today.

Molecular clock analysis of the DNA from hundreds of modern and ancient dogs suggests they were domesticated between around 20,000 and 22,000 years ago, when large ice sheets covered much of Eurasia and North America. The first dog identified in the archaeological record is a 14,000-year-old pup found in Bonn-Oberkassel, Germany, but it can be difficult to tell based on bones whether an animal was an early domestic dog or a wild wolf.

Despite the shared history of dogs and wolves, scientists have long thought these two species rarely mated and gave birth to hybrid offspring. As an evolutionary biologist and a molecular anthropologist who study domestic plants and animals, we wanted to take a new look at whether dog-wolf hybridization has really been all that uncommon.

Little interbreeding in the wild

Dogs are not exactly descended from modern wolves. Rather, dogs and wolves living today both derive from a shared ancient wolf population that lived alongside woolly mammoths and cave bears.

In most domesticated species, there are often clear, documented patterns of gene flow between the animals that live alongside humans and their wild counterparts. Where wild and domesticated animals’ habitats overlap, they can breed with each other to produce hybrid offspring. In these cases, the genes from wild animals are folded into the genetic variation of the domesticated population.

For example, pigs were domesticated in the Near East over 10,000 years ago. But when early farmers brought them to Europe, they hybridized so frequently with local wild boar that almost all of their Near Eastern DNA was replaced. Similar patterns can be seen in the endangered wild Anatolian and Cypriot mouflon that researchers have found to have high proportions of domestic sheep DNA in their genomes. It’s more common than not to find evidence of wild and domesticated animals interbreeding through time and sharing genetic material.

That wolves and dogs wouldn’t show that typical pattern is surprising, since they live in overlapping ranges and can freely interbreed.

Dog and wolf behavior are completely different, though, with wolves generally organized around a family pack structure and dogs reliant on humans. When hybridization does occur, it tends to be when human activities – such as habitat encroachment and hunting – disrupt pack dynamics, leading female wolves to strike out on their own and breed with male dogs. People intentionally bred a few “wolf dog” hybrid types in the 20th century, but these are considered the exception.

a wolfish looking dog lies on the ground behind a metal fence
Luna Belle, a resident of the Wolf Sanctuary of Pennsylvania, which is home to both wolves and wolf dogs.
Audrey Lin

Tiny but detectable wolf ancestry

To investigate how much gene flow there really has been between dogs and wolves after domestication, we analyzed 2,693 previously published genomes, making use of massive publicly available datasets.

These included 146 ancient dogs and wolves covering about 100,000 years. We also looked at 1,872 modern dogs, including golden retrievers, Chihuahuas, malamutes, basenjis and other well-known breeds, plus more unusual breeds from around the world such as the Caucasian ovcharka and Swedish vallhund.

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Finally, we included genomes from about 300 “village dogs.” These are not pets but are free-living animals that are dependent on their close association with human environments.

We traced the evolutionary histories of all of these canids by looking at maternal lineages via their mitochondrial genomes and paternal lineages via their Y chromosomes. We used highly sensitive computational methods to dive into the dogs’ and wolves’ nuclear genomes – that is, the genetic material contained in their cells’ nuclei.

We found the presence of wild wolf genes in most dog genomes and the presence of dog genes in about half of wild wolf genomes. The sign of the wolf was small but it was there, in the form of tiny, almost imperceptible chunks of continuous wolf DNA in dogs’ chromosomes. About two-thirds of breed dogs in our sample had wolf genes from crossbreeding that took place roughly 800 generations ago, on average.

While our results showed that larger, working dogs – such as sled dogs and large guardian dogs that protect livestock – generally have more wolf ancestry, the patterns aren’t universal. Some massive breeds such as the St. Bernard completely lack wolf DNA, but the tiny Chihuahua retains detectable wolf ancestry at 0.2% of its genome. Terriers and scent hounds typically fall at the low end of the spectrum for wolf genes.

a dog curled up on the sidewalk in a town
A street – or free-ranging – dog in Tbilisi, Georgia.
Alexkom000/Wikimedia Commons, CC BY

We were surprised that every single village dog we tested had pieces of wolf DNA in their genomes. Why would this be the case? Village dogs are free-living animals that make up about half the world’s dogs. Their lives can be tough, with short life expectancy and high infant mortality. Village dogs are also associated with pathogenic diseases, including rabies and canine distemper, making them a public health concern.

More often than predicted by chance, the stretches of wolf DNA we found in village dog genomes contained genes related to olfactory receptors. We imagine that olfactory abilities influenced by wolf genes may have helped these free-living dogs survive in harsh, volatile environments.

The intertwining of dogs and wolves

Because dogs evolved from wolves, all of dogs’ DNA is originally wolf DNA. So when we’re talking about the small pieces of wolf DNA in dog genomes, we’re not referring to that original wolf gene pool that’s been kicking around over the past 20,000 years, but rather evidence for dogs and wolves continuing to interbreed much later in time.

A wolf-dog hybrid with one of each kind of parent would carry 50% dog and 50% wolf DNA. If that hybrid then lived and mated with dogs, its offspring would be 25% wolf, and so on, until we see only small snippets of wolf DNA present.

The situation is similar to one in human genomes: Neanderthals and humans share a common ancestor around half a million years ago. However, Neanderthals and our species, Homo sapiens, also overlapped and interbred in Eurasia as recently as a few thousand generations ago, shortly before Neanderthals disappeared. Scientists can spot the small pieces of Neanderthal DNA in most living humans in the same way we can see wolf genes within most dogs.

two small tan dogs walking on pavement on a double lead leash
Even tiny Chihuahuas contain a little wolf within their doggy DNA.
Westend61 via Getty Images

Our study updates the previously held belief that hybridization between dogs and wolves is rare; interactions between these two species do have visible genetic traces. Hybridization with free-roaming dogs is considered a threat to conservation efforts of endangered wolves, including Iberian, Italian and Himalayan wolves. However, there also is evidence that dog-wolf mixing might confer genetic advantages to wolves as they adapt to environments that are increasingly shaped by humans.

Though dogs evolved as human companions, wolves have served as their genetic lifeline. When dogs encountered evolutionary challenges such as how to survive harsh climates, scavenge for food in the streets or guard livestock, it appears they’ve been able to tap into wolf ancestry as part of their evolutionary survival kit.The Conversation

Audrey T. Lin, Research Associate in Anthropology, Smithsonian Institution and Logan Kistler, Curator of Archaeobotany and Archaeogenomics, National Museum of Natural History, Smithsonian Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Science

October Meteor Showers Give Phoenix Skywatchers a Reason to Look Up

Phoenix skywatchers have several chances to catch October’s meteor showers. Here’s when to watch the Taurids and Orionids—and how moonlight affects the view.

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Last Updated on October 10, 2026 by Daily News Staff

PHOENIX — October is bringing several opportunities to spot shooting stars over the Valley, with the Draconids reaching their October 8–9 peak and more meteor activity ahead.

The Draconids remain active through October 10, although viewers should expect a light display as the peak passes. Under favorable conditions, the shower typically produces only a handful of meteors per hour. timeanddate.com

Illustration of Orionid meteor shower above Arizona mountains and saguaro cacti, with a sky chart labeling Orion, Betelgeuse, and the shower’s radiant.
An illustrated view of the Orionid meteor shower above the Arizona desert. The shower peaks October 21–22, 2026.

Next, the Southern Taurids have an annual activity peak around October 14. Known for occasional bright fireballs, the shower continues into November. The stronger Orionids peak on the night of October 21 into the morning of October 22, typically producing 10–20 meteors per hour under dark skies. A bright Moon will interfere with this year’s display. American Meteor Society

Phoenix Meteor Showers October 2026: When to Watch

The Orionids originate from debris left by Halley’s Comet. For Phoenix viewers, the best opportunity will be after moonset and before dawn, weather permitting. City lights will further reduce the number visible. amsmeteors.org

NASA recommends finding a viewing area away from streetlights, allowing about 30 minutes for eyes to adjust, and watching a broad stretch of sky. No telescope is needed—just a comfortable chair and patience. NASA Science

ECurious about what’s happening above us? Explore more space stories and science explainers in The Knowledge at STM Daily News.xplore more space, science and everyday

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unknown

Did Jackie Gleason See Aliens? Inside the Strange Nixon–UFO Legend

Jackie Gleason reportedly told his wife that President Richard Nixon arranged for him to view preserved extraterrestrial bodies at a Florida Air Force base. Here is what we know—and why the remarkable story remains unverified.

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The beloved comedian reportedly told his wife that President Richard Nixon arranged for him to view preserved extraterrestrial bodies at a Florida Air Force base. Decades later, the extraordinary story remains fascinating—but unverified.

Jackie Gleason and Richard Nixon portrayed against a mysterious nighttime military-base setting
Jackie Gleason’s alleged encounter with preserved alien bodies remains one of Hollywood’s strangest UFO legends.

Jackie Gleason is remembered as “The Great One,” the larger-than-life entertainer who turned bus driver Ralph Kramden into one of television’s most enduring characters on The Honeymooners. Away from the cameras, however, Gleason had another consuming interest: UFOs, psychic phenomena and the possibility of extraterrestrial life.

That interest eventually became the foundation of one of the strangest stories ever associated with an American president and a Hollywood celebrity. According to Gleason’s second wife, Beverly McKittrick, her husband came home late one night in 1973 and claimed that President Richard Nixon had helped him see the preserved bodies of extraterrestrial beings at Homestead Air Force Base in Florida.

Did Jackie Gleason really see aliens?

The honest answer is that we do not know. The allegation is remarkable, but the available evidence never rises above an uncorroborated story attributed to Gleason years after the supposed event.

Gleason’s fascination with UFOs was real

There is little question that Gleason took the UFO subject seriously. He reportedly assembled a substantial personal library devoted to UFOs, the paranormal and related mysteries. His unusual circular home in New York—often nicknamed “The Mothership”—only strengthened his public association with flying saucers, although its distinctive architecture is not evidence of an extraterrestrial encounter.

Gleason also had a genuine social connection with Nixon. The two men shared an interest in golf and spent time together in Florida. That documented friendship is the factual starting point from which the more sensational story grew.

The alleged trip to Homestead Air Force Base

McKittrick said that Gleason returned to their Florida home at about 11:30 one evening looking disturbed. According to her account, he told her that Nixon had arrived without the usual presidential entourage and taken him to Homestead Air Force Base, south of Miami.

Once there, Gleason allegedly entered a secured building where he saw small humanoid bodies preserved inside glass-topped containers. Published versions differ over the number of bodies and some physical details, but they generally describe child-sized beings with oversized heads.

Importantly, McKittrick did not claim to have accompanied the men or witnessed anything at the base. Her account was based entirely on what she said Gleason told her after returning home.

The story became public in 1983, years after the alleged visit and after the couple had divorced. It circulated widely through tabloid reporting, UFO publications and later books, gradually becoming part of UFO folklore.

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Why the story remains unverified

No authenticated photograph, visitor record, military document or firsthand statement from Nixon has emerged to confirm the alleged trip. Gleason also never provided investigators with a signed affidavit describing the experience.

UFO researcher Larry Bryant reportedly sought records from Homestead and tried to obtain a statement from Gleason, but those efforts produced no confirming documentation. Gleason’s refusal to address the account publicly has sometimes been portrayed as suspicious, but silence is not proof that an event occurred.

There is another important complication: McKittrick later expressed uncertainty about her former husband’s story.

During telephone interviews conducted by researcher Kenny Young in 2003, she stood by her recollection that Gleason told her he had seen “dead aliens.” She also acknowledged that, as the years passed, she wondered whether he might have invented the explanation because he had been out late. She declined to appear on camera and said the story should be authenticated first.

Her later comments do not establish that the account was false, but they considerably weaken any attempt to treat it as verified history.

Could a president have slipped away unnoticed?

Some versions of the legend emphasize that Nixon supposedly drove to Gleason’s house alone and then entered a military installation without his Secret Service detail. Presidents have occasionally sought privacy or slipped away from tightly managed schedules, but a secret nighttime excursion of this nature would have involved serious security and logistical obstacles.

The claim becomes even more difficult to accept when we consider what Nixon allegedly revealed. If the United States possessed extraterrestrial bodies, granting a comedian personal access to them would have represented an extraordinary breach of national security—with no apparent official purpose and no surviving documentation.

None of that makes the episode logically impossible. It does, however, mean that the story requires exceptionally strong evidence. That evidence has never appeared.

A compelling legend, not a confirmed encounter

The Jackie Gleason story endures because it combines three irresistible ingredients: a famous comedian fascinated by UFOs, a secretive American president and a nighttime visit to a military base containing an alleged government secret.

What can be established is that Gleason was deeply interested in UFOs, knew Nixon and was said by his former wife to have made an extraordinary claim. What cannot be established is that Nixon took him to Homestead Air Force Base or that preserved extraterrestrial bodies were ever stored there.

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So, did Jackie Gleason see aliens?

Perhaps he believed that he did—or perhaps he simply told an unforgettable story. Until corroborating evidence emerges, the alleged encounter belongs in the intriguing borderland between celebrity history and American UFO mythology.

Sources and further reading

Step into The Unknown, where STM Daily News explores the strange phenomena, unexplained encounters and enduring mysteries that continue to challenge what we think we know. From UFO sightings and paranormal events to historical mysteries and unusual scientific discoveries, we examine the stories, evidence and competing explanations—without losing our sense of wonder. https://stmdailynews.com/science/unknown/

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health and wellness

Lactose intolerance is actually the human norm – but racism, the US government and business interests have made it into a condition

Lactose intolerance is the global human norm, but Western dietary standards, government policies and commercial interests helped frame it as a medical deficiency.

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Close-up of spilled glass bottle of milk. Lactose intolerance is actually the human norm
The majority of the world is unable to process the lactose in milk without uncomfortable symptoms. Olga Miltsova/iStock via Getty Images Plus

Hilary Smith, University of Denver

Lactose intolerance makes drinking milk or eating ice cream a literal pain. For some people, eating a dairy treat can lead to bloating, nausea and diarrhea. You might’ve experienced its effects yourself. If so, you may think of lactose intolerance as a defect rather than the norm.

But did you know that most people in the world today are lactose intolerant – and that the condition itself was invented in the 1960s?

“Surely you mean discovered, not invented,” I hear you saying. I don’t. As a historian who has traced the origins of nutrition-science ideas, I have chosen the word “invented” on purpose.

Inventing lactose intolerance

Variations in people’s ability to digest lactose first came to scientists’ attention after American dairy producers found a way to rid themselves of a postwar milk surplus. To offload what they couldn’t sell, they looked to the government to intervene. And it did, buying the excess and embedding it in school lunches and other places with publicly funded meals.

Suddenly, many people who had not habitually drunk milk were consuming it regularly, including not only some Americans but also people overseas. Part of that same milk surplus found its way into school lunches in places such as Japan and Taiwan in the 1950s as the American government began to sell milk to allies during the Cold War.

Black and white photo of children in uniform eating lunch at their desks
Longshou Elementary School students in Taiwan in 1964 eat an American aid lunch for the first time. National Archives of Taiwan, CC BY-NC-SA

Many of the groups drinking milk regularly for the first time did not like it. In fact, it made them feel sick. Intrigued, scientists set up experiments to figure out why. In a 1966 study comparing how Black and white people incarcerated in Baltimore metabolized lactose, researchers found that Black participants had lower levels of lactase – the enzyme that breaks down lactose – in their guts.

To the white scientists conducting this study, the trouble that the Black prisoners had digesting milk looked like an “inborn error of metabolism.” They assumed that the normal human state was lactose tolerance and that the lactose intolerant had inherited a genetic mutation.

It was only after years more work with research participants of many races that experts realized that, as one National Institutes of Health official put it in 1981, “lactose intolerance is a normal physiological condition, shared by every adult animal except for certain ethnic and racial groups in man.” People of northern European descent, it turned out, were the weird ones. It was their ancestors who had passed down a genetic mutation – one that made them able to digest milk after infancy.

In short, what scientists discovered in the 1960s was that different bodies process milk differently. What they invented was the idea that lactose intolerance is a defect. Accepting that framing would mean nearly two-thirds of the human population – the estimated prevalence of lactose intolerance worldwide – is defective.

Instead of acknowledging that dairy-free diets can be healthy, people innovated ways to overcome this supposed disability so everyone could consume more.

Statue of cow dressed as Superman in an advertising display, two people working in the background
Milk is advertised in China as essential to health, even though most of the population is lactose intolerant. Ng Han Guan/AP Photo

Nutritional imperialism

Lactose intolerance is one example of what I call nutritional imperialism: a way of thinking that treats white diets as the norm and everyone else’s as an aberration.

Nutritional imperialism was common in the 20th century, when scientists thought that not only milk-rich but also meat-heavy diets were best; they considered diets outside of the United States and Europe too vegetarian. Some also argued that wheat flour, not rice, ought to be the universal staple.

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The same bias applied to bodies. Besides faulty lactose digestion, nonwhite bodies were accused of other failures, too, such as aldehyde dehydrogenase deficiency, an inability to digest alcohol quickly. The less technical term for this may be more familiar: Asian flush.

Such differences might have been thought of as variety, just another way of being human. Instead, each became a deficiency.

Many people today have inherited and perpetuated this way of thinking without knowing it, including those who are deemed deficient by it. In 1959, the director of Japan’s nutrition bureau declared that “rice-eating peoples” such as the Japanese were “resigned and passive” and could correct this by imitating Western diets and switching to wheat.

Grocery store aisle filled with various brands of milk
Milk is ubiquitous in grocery stores in China. Shwangtianyuan/Wikimedia Commons, CC BY-SA

Today, the most prominent scientist promoting the idea that Asian flush is a disease is a geneticist of Taiwanese descent who started a research consortium to study “the most common human enzymopathy in the world.”

The Chinese Nutrition Society placed a tall glass of milk next to its 2022 Food Guide Plate – never mind estimates that the vast majority of Han Chinese, the largest ethnic group in China and worldwide, are lactose intolerant.

Turning sickness back into difference

Science that pathologizes difference helps racism persist.

In recent years, white supremacists have embraced the concept of lactose intolerance as a distinguishing debility of nonwhite people. Social media users have copied and pasted a map of the geographic distribution of lactose tolerance originally published in the scientific journal Nature into racist chat threads on the online discussion forum 4chan.

In 2017, internet trolls disrupted an anti-racist art installation with neo-Nazi chants and messily downed jugs of milk to accentuate their white identity.

Turning a lactose-digestion difference into a deficiency has done more to reinforce narratives of racial hierarchy than to improve public health. So here’s a suggestion: If you enjoy eating dairy, keep doing it; if you don’t, don’t – and know that there is nothing wrong with you.

Hilary Smith, Professor of History, University of Denver

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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